Re: iSCSI: 2.2.6. Naming & mapping

["John Hufferd/San Jose/IBM" <hufferd@us.ibm.com>]

Peter,
As specified by Jim Hafner, there is no need and we should not  do what you
suggest.  We have talked this through before, many, many times, and the
answer has always come out the same.  PLEASE, lets not go there again.
.
.
.
John L. Hufferd


Peter Johansson <PJohansson@ACM.org>@ece.cmu.edu on 09/17/2000 11:14:16 AM

Sent by:  owner-ips@ece.cmu.edu


To:   IP Storage <IPS@ece.cmu.edu>
cc:
Subject:  Re: iSCSI: 2.2.6. Naming & mapping



At 07:45 PM 9/16/00, John Hufferd/San Jose/IBM wrote:

>As with Fibre Channel (and even multiple SCSI buss connections), once you
>have acuired a connection to the Storage Controller, you may address  LU
>0, to get the LU numbers that are authorize to that connection (with some
>Storage Controllers these are virtual Devices authorized by connection
>"port" and/or WWN of the initiator).  The values returned by the LU0 query
>are the unique LUNs related to that LU 0  (real or virtual).
>
>The Host SCSI layer can then obtain a unique ID from the EVPD page 83h.
>When the same unique ID is found on different paths then they have
>discovered an "Alternate Path".   All of this is normal SCSI, not
transport.

This is one of two methods I mentioned, an approach rooted in the command
set. I have no disagreement with the usefulness of vital product data for
this purpose.

>Since many Storage Controller create virtual volumes, and these are only
>visable to authorized Initiators,  and also unknown to the transport. It
>seems that we should keep to the same approach used by Fibre Channel et.
>al. and keep it away from the (iSCSI) transport.

I was unaware that iSCSI was targeted (no pun intended) solely at Storage
Controllers. If there are iSCSI methods to describe the existence of a
particular target's LUs PRIOR to session establishment, then it may also be
desirable to be able to discover unique IDs at a target or LU level at the
same time. Some clients may find it useful to make a decision at this
earlier point rather than after issuing a SCSI command. In any case, this
feature would be OPTIONAL and complementary to EVPD.




Regards,

Peter Johansson

Congruent Software, Inc.
98 Colorado Avenue
Berkeley, CA  94707

(510) 527-3926
(510) 527-3856 FAX

PJohansson@ACM.org